Cooler weather often means more inside workouts. Running 
on a treadmill does not have to be boring or less intense than your outside workout. In fact, running on a treadmill can be a great way to do an interval workout. An interval workout is one that varies the intensity by going faster and slower for certain amounts of time. This type of workout can increase calories burned, amp up your metabolism, and increase fitness – when compared to a workout that does not vary intensity.
Give this 30-minute workout a try. If the intensity is too much or not enough, adjust up or down. The goal is to vary the intensity over the entire workout.
- Minute 1: 4.0 mph
- Minute 2: 5.5 mph
- Minute 3: 6.0 mph
- Minute 4: 6.5 mph
- Minute 5: 7.0 mph
Repeat the above 5 more times for a total workout of 30 minutes.